Assessment of attached and unattached progeny concentrations of ²²²Rn/²²⁰Rn and their contribution to dose using deposition-based progeny sensors

The exposure of radiation from natural sources to population has become an important issue in terms of radiological protection. Mostly natural radiation comes from radon (²²²Rn), thoron (²²⁰Rn) and their solid short-lived daughter products that are the main threat to public health risk. The results presented in this paper are from a survey carried out in 40 villages of Jammu district, Sub-Mountainous region of Jammu and Kashmir, India, to quantify progeny concentration of radon and thoron using a passive time integrating, deposition-based technique. For estimating the total (attached + unattached) progeny concentration of radon/thoron, direct radon/thoron progeny sensors (DRPS/DTPS) have been used and only attached progeny concentration of radon/thoron has been measured by using wire-mesh capped direct radon/thoron progeny sensors (WM-DRPS/WM-DTPS). The study has been conducted for a period of 1 year during winter, rainy and summer seasons in all 112 dwellings. The exposure time of the sensors was 4 months. In this survey, the variability of progeny concentration of radon and thoron based upon variation in building construction materials and seasons-wise has also been discussed and efforts have been made to provide the reason for these variations. The highest level of progeny concentration of radon/thoron was found in the mud-type dwellings compared with dwellings made of concrete, cement and marble. Indoor and outdoor gamma dose rate (µSvh⁻¹) has also been measured and correlated indoor gamma annual effective dose (µSvy⁻¹) with progeny annual effective dose (µSvy⁻¹).